Pyroelectric detector, pyroelectric detection device, and electronic instrument

ABSTRACT

A pyroelectric detector includes a support member, a capacitor and a fixing part. The support member includes a first side and a second side opposite from the first side, with the first side facing a cavity. The capacitor includes a pyroelectric body between a first electrode and a second electrode such that an amount of polarization varies based on a temperature. The capacitor is mounted and supported on the second side of the support member with the first electrode being disposed on the second side of the support member. A thermal conductance of the first electrode is less than a thermal conductance of the second electrode. The fixing part supports the support member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2010-072079 filed on Mar. 26, 2010. The entire disclosure of JapanesePatent Application No. 2010-072079 is hereby incorporated herein byreference.

BACKGROUND

1. Technical Field

The present invention relates to a pyroelectric detector, a pyroelectricdetection device, and an electronic instrument or the like.

2. Related Art

Known thermo-optical detection devices include pyroelectric orbolometer-type infrared detection devices. An infrared detection deviceutilizes a change (pyroelectric effect or pyroelectronic effect) in theamount of spontaneous polarization of a pyroelectric material accordingto the light intensity (temperature) of received infrared rays to createan electromotive force (charge due to polarization) at both ends of thepyroelectric body (pyroelectric-type) or vary a resistance valueaccording to the temperature (bolometer-type) and detect the infraredrays. Compared with a bolometer-type infrared detection device, apyroelectric infrared detection device is complex to manufacture, buthas the advantage of excellent detection sensitivity.

A cell of a pyroelectric infrared detection device has a capacitor whichincludes a pyroelectric body connected to an upper electrode and a lowerelectrode, and various proposals have been made regarding the materialof the electrodes or the pyroelectric body (Japanese Laid-Open PatentPublication No. 2008-232896).

A capacitor which includes a ferroelectric body connected to an upperelectrode and a lower electrode is used in ferroelectric memory, andvarious proposals have been made regarding the material of theelectrodes or the ferroelectric body to be suitable for ferroelectricmemory (Japanese Laid-Open Patent Publication No. 2009-71242 andJapanese Laid-Open Patent Publication No. 2009-129972).

SUMMARY

A pyroelectric infrared detection device utilizes the effect(pyroelectric effect) whereby the amount of spontaneous polarization ofthe pyroelectric material varies according to temperature, and thereforediffers significantly from ferroelectric memory in having a structure inwhich heat does not readily escape from the capacitor.

An object of the several aspects of the present invention is to providea pyroelectric detector having a structure in which heat of a capacitorhaving a pyroelectric body does not readily escape via a support memberfor supporting the capacitor, and to provide a pyroelectric detectiondevice and an electronic instrument.

A pyroelectric detector according to one aspect of the present inventionincludes a support member, a capacitor and a fixing part. The supportmember includes a first side and a second side opposite from the firstside, with the first side facing a cavity. The capacitor includes apyroelectric body between a first electrode and a second electrode suchthat an amount of polarization varies based on a temperature. Thecapacitor is mounted and supported on the second side of the supportmember with the first electrode being disposed on the second side of thesupport member. A thermal conductance of the first electrode is lessthan a thermal conductance of the second electrode. The fixing partsupports the support member.

Through this configuration, the heat caused by infrared rays is readilytransmitted to the pyroelectric body via the first electrode, the heatof the pyroelectric body does not readily escape to the support membervia the second electrode, and the signal sensitivity of the pyroelectricdetector is enhanced. The first electrode positioned further toward thesupport member than the second electrode may be mounted directly on thefirst side of the support member, or may be mounted via another layer.

In the pyroelectric detector as described above, the first electrodepreferably has a greater thickness than the second electrode.

The thermal conductance G1 of the first electrode is expressed asG1=λ1/T1 (λ1: thermal conductivity; T1: thickness), and the thermalconductance G2 of the second electrode is expressed as G2=λ2/T2 (λ2:thermal conductivity; T2: thickness). When the thermal conductivity ofthe first and second electrodes is such that λ1=λ2, and the thickness T1of the first electrode is greater than the thickness T2 of the secondelectrode (T1>T2), a thermal conductance relationship whereby G1<G2 canbe satisfied.

In the pyroelectric detector as described above, the first electrode,the second electrode, and the pyroelectric body are preferablypreferentially-oriented in a prescribed crystal plane. The firstelectrode preferably has a seed layer for preferentially-orienting thepyroelectric body in the prescribed crystal plane. The second electrodepreferably has an orientation alignment layer in a position contactingthe pyroelectric body with crystal orientation of the orientationalignment layer being aligned with crystal orientation of thepyroelectric body. The seed layer preferably has a greater thicknessthan the orientation alignment layer.

The seed layer and the orientation alignment layer are sometimes formedfrom the same material or the same type of material, for example, forthe sake of the orientation functions thereof. When the seed layer isformed having a greater thickness than the orientation alignment layer,the thermal conductance of the seed layer in the first electrode iseasily made less than the thermal conductance of the orientationalignment layer in the second electrode, and the relationship G1<G2 iseasily obtained.

In the pyroelectric detector as described above, the first electrodefurther preferably includes an orientation control layer forpreferentially-orienting the seed layer in the prescribed crystal plane,the orientation control layer being disposed between the support memberand the seed layer.

Through this configuration, the presence of the orientation controllayer enables the seed layer to have the same preferred orientationdirection as the orientation control layer, and the characteristics ofthe seed layer are enhanced. There are also at least two layers of firstelectrode with respect to at least one layer of second electrode, andthe relationship G1<G2 is easily obtained.

In the pyroelectric detector as described above, the first electrodepreferably further includes a first reducing gas barrier layer havingbarrier properties with respect to a reducing gas, the first reducinggas barrier layer being disposed between the seed layer and theorientation control layer.

The characteristics of the pyroelectric body of the capacitor aredegraded when oxygen deficit occurs due to reducing gas. Reductiveobstructive factors from the side of the support member can be blockedby the first reducing gas barrier layer in the first electrodepositioned on the support member side in the capacitor. The firstreducing gas barrier layer may also have the same preferred orientationdirection as the orientation control layer. There are also at leastthree layers of first electrode with respect to at least one layer ofsecond electrode, and the relationship G1<G2 is easily obtained.

In the pyroelectric detector as described above, the first electrodepreferably further includes an adhesive layer between the orientationcontrol layer and the support member.

Since the orientation control properties of the orientation controllayer degrade when there are surface irregularities or voids against thebase layer, an adhesive layer is provided to maintain the orientationcontrol properties. There are also at least four layers of firstelectrode with respect to at least one layer of second electrode, andthe relationship G1<G2 is easily obtained. The adhesive layer is a layerhaving high adhesion to the support member in comparison with theorientation control layer.

In the pyroelectric detector as described above, the second electrodepreferably further includes a second reducing gas barrier layer havingbarrier properties with respect to a reducing gas, with the orientationalignment layer being disposed between the second reducing gas barrierlayer and the pyroelectric body.

Through this configuration, reductive obstructive factors from above thecapacitor can be blocked by the second reducing gas barrier layer in thesecond electrode. The second reducing gas barrier layer may have thesame preferred orientation direction as the orientation alignment layer.

In the pyroelectric detector as described above, the second electrodepreferably further includes a low-resistance layer, with the secondreducing gas barrier layer being disposed between the low-resistancelayer and the orientation control layer. The orientation control layerand the low-resistance layer are preferably made of the same material,and the orientation control layer has a greater thickness than thelow-resistance layer.

Through this configuration, it is possible to overcome the problem ofincreased contact resistance when the second reducing gas barrier layeris connected to a wiring plug, and an orientation control layer having agreater thickness than the low-resistance layer is added to the secondelectrode. The relationship G1<G2 is therefore easily obtained. Thelow-resistance layer is a layer having low contact resistance to thewiring plug connected to the second electrode, in comparison with thesecond reducing gas barrier layer. The low-resistance layer may alsohave the same preferred orientation direction as the second reducing gasbarrier layer.

In the pyroelectric detector as described above, the first reducing gasbarrier layer and the second reducing gas barrier layer are preferablymade of the same material, and the first reducing gas barrier layer hasa greater thickness than the second reducing gas barrier layer.

Through this configuration, since the first electrode has a greaterthickness than the second electrode in terms of total layer thickness,the relationship G1<G2 is easily obtained.

In the pyroelectric detector as described above, the first reducing gasbarrier layer and the second reducing gas barrier layer are preferablymade of the same material, and the second reducing gas barrier layer hasa greater thickness than the first reducing gas barrier layer.

By thus increasing the thickness of the second reducing gas barrierlayer to enhance the barrier properties thereof, a particularenhancement is gained in the effects whereby reductive obstructivefactors from the wiring plug can be blocked. Through this configuration,the thermal conductance of the first electrode increases in comparisonwith the first and second reducing gas barrier layers, but by adjustingthe layer thickness or the properties (thermal conductivity) of theother materials, the relationship G1<G2 can easily be obtained.

In the pyroelectric detector as described above, the prescribed crystalplane is preferably a (111) plane. The (100) plane or another plane maybe preferred over the (111) plane as the crystal plane in order toincrease the pyroelectric coefficient, but by making the crystal planethe (111) plane, the polarity with respect to the applied fielddirection is easily controlled.

The pyroelectric detector as described above preferably further includesa light-absorbing member configured to transmit heat obtained byabsorption of light to the capacitor, the light-absorbing member beingdisposed on an upstream side of the capacitor with respect to anincidence path of light incident to the second electrode of thecapacitor. The second electrode is preferably configured to reflect thelight passed through the light-absorbing member to the light-absorbingmember.

Through this configuration, unnecessarily transmitted light can bereturned to the light-absorbing member so as to contribute to heatevolution. The position of a reflecting plate (second electrode) can beset so that multiple reflection occurs at a distance of λ/4, where λ isthe detection wavelength. The function of the reflecting plate is takenon by the metal closest to the light-absorbing member in the secondelectrode.

A pyroelectric detection device according to another aspect of thepresent invention includes a plurality of the pyroelectric detectorsaccording to claim 1 arranged in two dimensions along two axes. In thispyroelectric detection device, the detection sensitivity is increased inthe pyroelectric detector of each cell, and a distinct light(temperature) distribution image can therefore be provided.

An electronic instrument according to another aspect of the presentinvention has the pyroelectric detector or pyroelectric detection devicedescribed above, and by using one or a plurality of cells of thepyroelectric detector as a sensor, the electronic instrument is mostsuitable in thermography for outputting a light (temperature)distribution image, in automobile navigation and surveillance cameras aswell as object analysis instruments (measurement instruments) foranalyzing (measuring) physical information of objects, in securityinstruments for detecting fire or heat, in FA (Factory Automation)instruments provided in factories or the like, and in otherapplications.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a simplified sectional view showing the structure of thecapacitor of the pyroelectric infrared detector according to anembodiment of the present invention;

FIG. 2 is a simplified plan view showing the pyroelectric infrareddetection device according to an embodiment of the present invention;

FIG. 3 is a simplified sectional view showing the pyroelectric detectorof one cell of the pyroelectric infrared detection device shown in FIG.2;

FIG. 4 is a simplified sectional view showing a manufacturing step, andshows the support member and infrared detection element formed on thesacrificial layer;

FIG. 5 is a simplified sectional view showing a modification in whichthe reducing gas barrier properties in the vicinity of the wiring plugare enhanced;

FIG. 6 is a block diagram showing the electronic instrument whichincludes the thermo-optical detector or thermo-optical detection device;and

FIGS. 7A and 7B are views showing an example of the configuration of apyroelectric detection device in which pyroelectric detectors arearranged in two dimensions.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Preferred embodiments of the present invention will be described indetail. The embodiments described below do not unduly limit the scope ofthe present invention as recited in the claims, and all of theconfigurations described in the embodiments are not necessarilyessential means of achievement of the present invention.

1. Pyroelectric Infrared Detection Device

FIG. 2 shows a pyroelectric infrared detection device (one example of apyroelectric detection device) in which a plurality of cells ofpyroelectric infrared detectors (one example of pyroelectric detectors)is arranged along two orthogonal axes, each cell being provided with thecapacitor structure (described hereinafter) shown in FIG. 1. Apyroelectric infrared detection device may also be formed by apyroelectric infrared detector of a single cell. In FIG. 2, a pluralityof posts 104 is provided upright from a base part (also referred to as afixing part) 100, and pyroelectric infrared detectors 200, each cell ofwhich is supported by two posts 104, for example, are arranged along twoorthogonal axes. The area occupied by each cell of pyroelectric infrareddetectors 200 is 30×30 μm, for example.

As shown in FIG. 2, each pyroelectric infrared detector 200 includes asupport member (membrane) 210 linked to two posts 104, and an infrareddetection element (one example of a pyroelectric detection element) 220.The area occupied by the pyroelectric infrared detection element 220 ofone cell is 10×10 μm, for example.

Besides being connected to the two posts 104, the pyroelectric infrareddetector 200 of each cell is in a non-contacting state, a cavity 102(see FIG. 3) is formed below the pyroelectric infrared detector 200, andopen parts 102A communicated with the cavity 102 are provided on theperiphery of the pyroelectric infrared detector 200 in plan view. Thepyroelectric infrared detector 200 of each cell is thereby thermallyseparated from the base part 100 as well as from the pyroelectricinfrared detectors 200 of other cells.

The support member 210 has a mounting part 210A for mounting andsupporting the pyroelectric infrared detection element 220, and two arms210B linked to the post 104. The two arms 210B are formed so as toextend redundantly and with a narrow width in order to thermallyseparate the pyroelectric infrared detection element 220.

FIG. 2 is a plan view which omits the members above the wiring layersconnected to the upper electrodes, and FIG. 2 shows a first electrode(lower electrode) wiring layer 222 and a second electrode (upperelectrode) wiring layer 224 connected to the pyroelectric infrareddetection element 220. The first and second electrode wiring layers 222,224 extend along the arms 210B, and are connected to a circuit insidethe base part 100 via the posts 104. The first and second electrodewiring layers 222, 224 are also formed so as to extend redundantly andwith a narrow width in order to thermally separate the pyroelectricinfrared detection element 220.

2. Overview of the Pyroelectric Infrared Detector

FIG. 3 is a sectional view showing the pyroelectric infrared detector200 shown in FIG. 2. FIG. 4 is a partial sectional view showing thepyroelectric infrared detector 200 during the manufacturing process. InFIG. 4, the cavity 102 is embedded by a sacrificial layer 150. Thesacrificial layer 150 is present from before the step of forming thesupport member 210 and the pyroelectric infrared detection element 220until after this formation step, and is removed by isotropic etchingafter the step of forming the pyroelectric infrared detection element220.

As shown in FIG. 3, the base part 100 includes a substrate, e.g., asilicon substrate 110, and a spacer layer 120 formed by an interlayerinsulation layer on the silicon substrate 110. The post 104 is formed byetching the spacer layer 120. A plug 106 connected to one of the firstand second electrode wiring layers 222, 224 may be disposed at the post104. The plug 106 is connected to a row selection circuit (row driver)provided to the silicon substrate 110, or a read circuit for readingdata from an optical detector via a column line. The cavity 102 isformed at the same time as the post 104 by etching the spacer layer 120.The open parts 102A shown in FIG. 2 are formed by pattern etching thesupport member 210.

The pyroelectric infrared detection element 220 mounted on the supportmember 210 includes a capacitor 230. The capacitor 230 includes apyroelectric body 232, a first electrode (lower electrode) 234 connectedto the lower surface of the pyroelectric body 232, and a secondelectrode (upper electrode) 236 connected to the upper surface of thepyroelectric body 232. The first electrode 234 may include an adhesivelayer 234D for increasing adhesion to a first layer member (e.g., SiO₂)of the support member 210.

The capacitor 230 is covered by a reducing gas barrier layer 240 forsuppressing penetration of reducing gas (hydrogen, water vapor, OHgroups, methyl groups, and the like) into the capacitor 230 during stepsafter formation of the capacitor 230. The reason for this is that thepyroelectric body (e.g., PZT or the like) 232 of the capacitor 230 is anoxide, and when an oxide is reduced, oxygen deficit occurs and thepyroelectric effects are compromised.

The reducing gas barrier layer 240 includes a first barrier layer 242and a second barrier layer 244, as shown in FIG. 4. The first barrierlayer 242 can be formed by forming a layer of aluminum oxide Al₂O₃, forexample, by sputtering. Since reducing gas is not used in sputtering, noreduction of the capacitor 230 occurs. The second barrier layer 244 canbe formed by forming a layer of aluminum oxide Al₂O₃, for example, byAtomic Layer Chemical Vapor Deposition (ALCVD), for example. Common CVD(Chemical Vapor Deposition) methods use reducing gas, but the capacitor230 is isolated from the reducing gas by the first barrier layer 242.

The total layer thickness of the reducing gas barrier layer 240 hereinis 50 to 70 nm, e.g., 60 nm. At this time, the layer thickness of thefirst barrier layer 242 formed by CVD is greater than that of the secondbarrier layer 244 formed by Atomic Layer Chemical Vapor Deposition(ALCVD), and is 35 to 65 nm, e.g., 40 nm, at minimum. In contrast, thelayer thickness of the second barrier layer 244 formed by Atomic LayerChemical Vapor Deposition (ALCVD) can be reduced; for example, a layerof aluminum oxide Al₂O₃ is formed having a thickness of 5 to 30 nm,e.g., 20 nm. Atomic Layer Chemical Vapor Deposition (ALCVD) hasexcellent embedding characteristics in comparison with sputtering andother methods, and can therefore be adapted for miniaturization, and thereducing gas barrier properties in the first and second barrier layers242, 244 can be enhanced. The first barrier layer 242 formed bysputtering is not fine in comparison with the second barrier layer 244,but this aspect contributes to lowering the heat transfer rate thereof,and dissipation of heat from the capacitor 230 can therefore beprevented.

An interlayer insulation layer 250 is formed on the reducing gas barrierlayer 240. Hydrogen gas, water vapor, or other reducing gas usually isformed when the starting material gas (TEOS) of the interlayerinsulation layer 250 chemically reacts. The reducing gas barrier layer240 provided on the periphery of the capacitor 230 protects thecapacitor 230 from the reducing gas that occurs during formation of theinterlayer insulation layer 250.

The first electrode (lower electrode) wiring layer 222 and secondelectrode (upper electrode) wiring layer 224 shown in FIG. 2 as well aredisposed on the interlayer insulation layer 250. A first contact hole252 and second contact hole 254 are formed in advance in the interlayerinsulation layer 250 before formation of the electrode wiring. At thistime, a contact hole is formed in the same manner in the reducing gasbarrier layer 240 as well. The first electrode (lower electrode) 234 andthe first electrode wiring layer 222 are made continuous by a first plug226 embedded in the first contact hole 252. The second electrode (upperelectrode) 236 and the second electrode wiring layer 224 are madecontinuous in the same manner by a second plug 228 embedded in thesecond contact hole 254.

When the interlayer insulation layer 250 is not present in thisarrangement, during pattern etching of the first electrode (lowerelectrode) wiring layer 222 and the second electrode (upper electrode)wiring layer 224, the second barrier layer 244 of the reducing gasbarrier layer 240 beneath is etched, and the barrier properties thereofare reduced. The interlayer insulation layer 250 may be necessary inorder to secure the barrier properties of the reducing gas barrier layer240.

The interlayer insulation layer 250 preferably has a low hydrogencontent. The interlayer insulation layer 250 is therefore degassed byannealing. The hydrogen content of the interlayer insulation layer 250is thereby made lower than that of a passivation layer 260 for coveringthe first and second electrode wiring layers 222, 224.

Since the reducing gas barrier layer 240 at the top of the capacitor 230is devoid of contact holes and closed when the interlayer insulationlayer 250 is formed, the reducing gas during formation of the interlayerinsulation layer 250 does not penetrate into the capacitor 230. However,the barrier properties decline after the contact hole is formed in thereducing gas barrier layer 240. As an example of a technique forpreventing this phenomenon, the first and second plugs 226, 228 areformed by a plurality of layers 228A, 228B (only the second plug 228 isshown in FIG. 4), as shown in FIG. 4, and a barrier metal layer is usedin the first layer 228A. Reducing gas barrier properties are ensured bythe barrier metal of the first layer 228A. Highly diffusible metals suchas titanium Ti are not preferred as the barrier metal of the first layer228A, and titanium aluminum nitride TiAlN, which has minimaldiffusibility and high reducing gas barrier properties, can be used. Areducing gas barrier layer 290 may be additionally provided so as tosurround at least the second plug 228 as shown in FIG. 5, as a methodfor stopping the penetration of reducing gas from the contact hole. Thisreducing gas barrier layer 290 may also serve as the barrier metal 228Aof the second plug 228, or the barrier metal 228A may be removed. Thereducing gas barrier layer 290 may also coat the first plug 226.

The SiO₂ or SiN passivation layer 260 is provided so as to cover thefirst and second electrode wiring layers 222, 224. An infrared-absorbingbody (one example of a light-absorbing member) 270 is provided on thepassivation layer 260 above at least the capacitor 230. The passivationlayer 260 is also formed from SiO₂ or SiN, but is preferably formed froma different type of material which has a high etching selection ratiowith respect to the passivation layer 260 below, due to the need forpattern etching of the infrared-absorbing body 270. Infrared rays areincident on the infrared-absorbing body 270 from the direction of thearrow in FIG. 2, and the infrared-absorbing body 270 evolves heat inaccordance with the amount of infrared rays absorbed. This heat istransmitted to the pyroelectric body 232, whereby the amount ofspontaneous polarization of the capacitor 230 varies according to theheat, and the infrared rays can be detected by detecting the charge dueto the spontaneous polarization. The infrared-absorbing body 270 is notlimited to being provided separately from the capacitor 230, and neednot be provided separately in a case in which the infrared-absorbingbody 270 is present within the capacitor 230.

Even when reducing gas is generated during CVD formation of thepassivation layer 260 or the infrared-absorbing body 270, the capacitor230 is protected by the reducing gas barrier layer 240 and the barriermetals in the first and second plugs 226, 228.

A reducing gas barrier layer 280 is provided so as to cover the externalsurface of the pyroelectric infrared detector 200 which includes theinfrared-absorbing body 270. The reducing gas barrier layer 280 must beformed with a smaller thickness than the reducing gas barrier layer 240,for example, in order to increase the transmittance of infrared rays (inthe wavelength spectrum of 8 to 14 μm) incident on theinfrared-absorbing body 270. For this purpose, Atomic Layer ChemicalVapor Deposition (ALCVD) is used, which is capable of adjusting thelayer thickness at a level corresponding to the size of an atom. Thereason for this is that the layer formed by a common CVD method is toothick, and infrared transmittance is adversely affected. In the presentembodiment, a layer is formed having a thickness of 10 to 50 nm, e.g.,20 nm, from aluminum oxide Al₂O₃, for example. As described above,Atomic Layer Chemical Vapor Deposition (ALCVD) has excellent embeddingcharacteristics in comparison with sputtering and other methods, and istherefore adapted to miniaturization, a precise layer can be formed atthe atomic level, and reducing gas barrier properties can be increasedeven in a thin layer.

On the side of the base part 100, an etching stop layer 130 for useduring isotropic etching of the sacrificial layer 150 (see FIG. 4)embedded in the cavity 102 in the process of manufacturing thepyroelectric infrared detector 200 is formed on a wall part for definingthe cavity 102, i.e., a side wall 104A and a bottom wall 100A fordefining the cavity. An etching stop layer 140 is formed in the samemanner on a lower surface (upper surface of the sacrificial layer 150)of the support member 210. In the present embodiment, the reducing gasbarrier layer 280 is formed from the same material as the etching stoplayers 130, 140. In other words, the etching stop layers 130, 140 alsohave reducing gas barrier properties. The etching stop layers 130, 140are also formed by forming layers of aluminum oxide Al₂O₃ at a thicknessof 20 to 50 nm by Atomic Layer Chemical Vapor Deposition (ALCVD).

Since the etching stop layer 140 has reducing gas barrier properties,when the sacrificial layer 150 is isotropically etched by hydrofluoricacid in a reductive atmosphere, it is possible to keep the reducing gasfrom passing through the support member 210 and penetrating into thecapacitor 230. Since the etching stop layer 130 for covering the basepart 100 has reducing gas barrier properties, it is possible to keep thetransistors or wiring of the circuit in the base part 100 from beingreduced and degraded.

3. Structure of the Capacitor 3.1 Thermal Conductance

FIG. 1 is a simplified sectional view showing the structure of thecapacitor 230 of the present embodiment in further detail. As describedabove, the capacitor 230 includes a pyroelectric body 232 between thefirst electrode (lower electrode) 234 and the second electrode (upperelectrode) 236. The capacitor 230 is mounted and supported on a secondsurface or second side (upper surface or upper side in FIG. 1) whichfaces a first surface or first side (lower surface or upper side inFIG. 1) at which the support member 210 faces the cavity 102. Infraredrays can be detected by utilizing a change (pyroelectric effect orpyroelectronic effect) in the amount of spontaneous polarization of thepyroelectric body 232 according to the light intensity (temperature) ofthe incident infrared rays. In the present embodiment, the incidentinfrared rays are absorbed by the infrared-absorbing body 270, heat isevolved by the infrared-absorbing body 270, and the heat evolved by theinfrared-absorbing body 270 is transmitted via a solid heat transferpath between the infrared-absorbing body 270 and the pyroelectric body232.

In the capacitor 230 of the present embodiment, the thermal conductanceC1 of the first electrode (lower electrode) 234 adjacent to the supportmember 210 is less than the thermal conductance C2 of the secondelectrode (upper electrode) 236. Through this configuration, the heatcaused by the infrared rays is readily transmitted to the pyroelectricbody 232 via the second electrode (upper electrode) 236, the heat of thepyroelectric body 232 does not readily escape to the support member 210via the first electrode (lower electrode) 234, and the signalsensitivity of the infrared detection element 220 is enhanced.

In the support member 210 of the present embodiment on which thecapacitor 230 is mounted, since residual stress causes curvature tooccur when a single layer is used as shown in FIGS. 1 and 4, the supportmember 210 is formed by a plurality of layers, e.g., three layers, sothat the stress that causes curvature is cancelled out by the residualstresses of both tension and compression.

In order from the capacitor 230 side, a first layer member 212 iscomposed of an oxide layer (e.g., SiO₂), a second layer member 214 iscomposed of a nitride layer (e.g., Si₃N₄), and a third layer member 216is composed of an oxide layer (e.g., SiO₂, the same as the first layermember 212). Since the oxide layers and the nitride layer are stressedin opposite directions, the stress which causes curvature in the supportmember can be cancelled out. Since a nitride layer (e.g., Si₃N₄) hasreducing gas barrier properties, the second layer member 214 of thesupport member 210 also functions to block reductive obstructive factorsfrom penetrating from the side of the support member 210 to thepyroelectric body 232 of the capacitor 230.

The structure of the capacitor 230 having the characteristics describedabove will be described in further detail with reference to FIG. 1.First, the thickness T1 of the first electrode (lower electrode) 234 isgreater than that of the second electrode (upper electrode) 236 (T1>T2).The thermal conductance G1 of the first electrode (lower electrode) 234is such that G1=λ1/T1, where λ1 is the thermal conductivity of the firstelectrode (lower electrode) 234. The thermal conductance G2 of thesecond electrode (upper electrode) 236 is such that G2=λ2/T2, where λ2is the thermal conductance of the second electrode (upper electrode)236.

In order to obtain a thermal conductance relationship of C1<C2, when thefirst and second electrodes 234, 236 are both formed from the samesingle material, such as platinum Pt or iridium Ir, then λ1=λ2, andT1>T2 from FIG. 1. The relationship G1<G2 can therefore be satisfied.

A case in which the first and second electrodes 234, 236 are each formedfrom the same material will first be considered. In the capacitor 230,in order for the crystal direction of the pyroelectric body 232 to bealigned, it is necessary to align the crystal lattice level of theboundary of the lower layer on which the pyroelectric body 232 is formedwith the first electrode 234. In other words, although the firstelectrode 234 has the function of a crystal seed layer, platinum Pt hasstrong self-orienting properties and is therefore preferred as the firstelectrode 234. Iridium Ir is also suitable as a seed layer material.

In the second electrode (upper electrode) 236, the crystal orientationsare preferably continuously related from the first electrode 234 throughthe pyroelectric body 232 and the second electrode 236, without breakingdown the crystal properties of the pyroelectric body 232. The secondelectrode 236 is therefore preferably formed from the same material asthe first electrode 234.

When the second electrode 236 is thus formed by the same material, e.g.,Pt, Ir, or another metal, as the first electrode 234, the upper surfaceof the second electrode 236 can be used as a reflective surface. In thiscase, as shown in FIG. 1, the distance L from the top surface of theinfrared-absorbing body 270 to the top surface of the second electrode236 is preferably λ/4 (where λ is the detection wavelength of infraredrays). Through this configuration, multiple reflection of infrared raysof the detection wavelength λ occurs between the top surface of theinfrared-absorbing body 270 and the top surface of the second electrode236, and infrared rays of the detection wavelength λ can therefore beefficiently absorbed by the infrared-absorbing body 270.

3.2 Electrode Multilayer Structure

The structure of the capacitor 230 of the present embodiment shown inFIG. 1 will next be described. In the capacitor 230 shown in FIG. 1, thepreferred orientation directions of the pyroelectric body 232, the firstelectrode 234, and the second electrode 236 are aligned with the (111)orientation, for example. Through a preferred orientation in the (111)plane direction, the orientation rate of (111) orientation with respectto other plane directions is controlled to 90% or higher, for example.The (100) orientation or other orientation is more preferred than the(111) orientation in order to increase the pyroelectric coefficient, butthe (111) orientation is used so as to make polarization easy to controlwith respect to the applied field direction. However, the preferredorientation direction is not limited to this configuration.

The first electrode 234 may include, in order from the support member210, an orientation control layer (e.g., Ir) 234A for controlling theorientation so as to give the first electrode 234 a preferredorientation in the (111) plane, for example, a first reducing gasbarrier layer (e.g., IrOx) 234B, and a preferentially-oriented seedlayer (e.g., Pt) 234C.

The second electrode 236 may include, in order from the pyroelectricbody 232, an orientation alignment layer (e.g., Pt) 236A in which thecrystal alignment is aligned with the pyroelectric body 232, a secondreducing gas barrier layer (e.g., IrOx) 236B, and a low-resistance layer(e.g., Ir) 236C for lowering the resistance of the bonded surface withthe second plug 228 connected to the second electrode 236.

The first and second electrodes 234, 236 of the capacitor 230 areprovided with a multilayer structure in the present embodiment so thatthe pyroelectric infrared detection element 220 is processed withminimal damage and without reducing the capability thereof despite thesmall heat capacity thereof, the crystal lattice levels are aligned ateach boundary, and the pyroelectric body (oxide) 232 is isolated fromreducing gas even when the periphery of the capacitor 230 is exposed toa reductive atmosphere during manufacturing or use.

The pyroelectric body 232 is formed by growing a crystal of PZT (leadzirconate titanate: generic name for Pb(Zr, Ti)O₃), PZTN (generic namefor the substance obtained by adding Nb to PZT), or the like with apreferred orientation in the (111) plane direction, for example. The useof PZTN is preferred, because even a thin layer is not readily reduced,and oxygen deficit can be suppressed. In order to obtain directionalcrystallization of the pyroelectric body 232, directionalcrystallization is performed from the stage of forming the firstelectrode 234 as the layer under the pyroelectric body 232.

The Ir layer 234A for functioning as an orientation control layer istherefore formed on the lower electrode 234 by sputtering. A titaniumaluminum nitride (TiAlN) layer or a titanium nitride (TiN) layer, forexample, as the adhesive layer 234D may also be formed under theorientation control layer 234A, as shown in FIG. 1. The reason for thisis that adhesion may be difficult to maintain, depending on the materialof the support member 210. When the first layer member 212 of thesupport member 210 positioned beneath the adhesive layer 234D is formedfrom SiO₂, the first layer member 212 is preferably formed by anamorphous material or a material having smaller grains than polysilicon.The smoothness of the surface of the support member 210 on which thecapacitor 230 is mounted can thereby be maintained. When the surface onwhich the orientation control layer 234A is formed is rough, theirregularities of the rough surface are reflected in the growth of thecrystal, and a rough surface is therefore not preferred.

In order to isolate the pyroelectric body 232 from reductive obstructivefactors from below the capacitor 230, the IrOx layer 234B forfunctioning as a reducing gas barrier layer in the first electrode 234is used together with the second layer member (e.g., Si₃N₄) 214 of thesupport member 210, and the etching stop layer (e.g., Al₂O₃) 140 of thesupport member 210, which exhibit reducing gas barrier properties. Thereducing gas used in degassing from the base part 100 during baking orother annealing steps of the pyroelectric body (ceramic) 232, or in theisotropic etching step of the sacrificial layer 150, for example, is areductive obstructive factor.

Evaporation vapor sometimes formed inside the capacitor 230 in thebaking step of the pyroelectric body 232 and during otherhigh-temperature processing, but an escape route for this vapor ismaintained by the first layer member 212 of the support member 210, asindicated by the arrow in FIG. 4. In other words, in order to allowevaporation vapor formed inside the capacitor 230 to escape, it isbetter to provide gas barrier properties to the second layer member 214than to provide gas barrier properties to the first layer member 212.

The IrOx layer 234B as such has minimal crystallinity, but the IrOxlayer 234B is in a metal-metal oxide relationship with the Ir layer 234Aand thus has good compatibility therewith, and can therefore have thesame preferred orientation direction as the Ir layer 234A.

The Pt layer 234C for functioning as a seed layer in the first electrode234 is a seed layer for the preferred orientation of the pyroelectricbody 232, and has the (111) orientation. In the present embodiment, thePt layer 234C has a two-layer structure. The first Pt layer forms thebasis of the (111) orientation, microroughness is formed on the surfaceby the second Pt layer, and the Pt layer 234C thereby functions as aseed layer for preferred orientation of the pyroelectric body 232. Thepyroelectric body 232 is in the (111) orientation after the fashion ofthe seed layer 234C.

In the second electrode 236, since the boundaries of sputtered layersare physically rough, trap sites occur, and there is a risk of degradedcharacteristics, the lattice alignment is reconstructed on the crystallevel so that the crystal orientations of the first electrode 234, thepyroelectric body 232, and the second electrode 236 are continuouslyrelated.

The Pt layer 236A in the second electrode 236 is formed by sputtering,but the crystal direction of the boundary immediately after sputteringis not continuous. Therefore, an annealing process is subsequentlyperformed to re-crystallize the Pt layer 236A. In other words, the Ptlayer 236A functions as an orientation alignment layer in which thecrystal orientation is aligned with the pyroelectric body 232.

The IrOx layer 2368 in the second electrode 236 functions as a barrierfor factors which degrade the reducing properties from above thecapacitor 230. Since the IrOx layer 2368 has a high resistance value,the Ir layer 236C in the second electrode 236 is used to lower theresistance value with respect to the second plug 228. The Ir layer 236Cis in a metal oxide-metal relationship with the IrOx layer 2368 and thushas good compatibility therewith, and can therefore have the samepreferred orientation direction as the IrOx layer 236B.

In the present embodiment, the first and second electrodes 234, 236 thushave multiple layers arranged in the sequence Pt, IrOx, Ir from thepyroelectric body 232, and the materials forming the first and secondelectrodes 234, 236 are arranged symmetrically about the pyroelectricbody 232.

However, the thicknesses of each layer of the multilayer structuresforming the first and second electrodes 234, 236 are asymmetrical aboutthe pyroelectric body 232. The total thickness T1 of the first electrode234 and the total thickness T2 of the second electrode 236 satisfy therelationship (T1>T2) as also described above. The thermal conductivitiesof the Ir layer 234A, IrOx layer 2348, and Pt layer 234C of the firstelectrode 234 are designated as A1, 22, and 23, respectively, and thethicknesses thereof are designated as T11, T12, and T13, respectively.The thermal conductivities of the Ir layer 236C, IrOx layer 2368, and Ptlayer 236A of the second electrode 236 are also designated as λ1, λ2,and λ3, respectively, and the thicknesses thereof are designated as T21,T22, and T23, respectively.

When the thermal conductances of the Ir layer 234A, IrOx layer 234B, andPt layer 234C of the first electrode 234 are designated as G11, G12, andG13, respectively, G11=λ1/T11, G12=λ2/T12, and G13=λ3/T13. When thethermal conductances of the Ir layer 236C, IrOx layer 236B, and Pt layer236A of the second electrode 236 are designated as G21, G22, and G23,respectively, G21=λ1/T21, G22=λ2/T22, and G23=λ3/T23.

Since 1/G1=(1/G11)+(1/G12)+(1/G13), the total thermal conductance G1 ofthe first electrode 234 is expressed by the equation (1) below.

G1=(G11×G12×G13)/(G11×G12+G12×G13+G11×G13)  (1)

In the same manner, since 1/G2=(1/G21)+(1/G22)+(1/G23), the totalthermal conductance G2 of the second electrode 236 is expressed by theequation (2) below.

G2=(G21×G22×G23)/(G21×G22+G22×G23+G21×G23)  (2)

The thicknesses of each layer of the multilayer structure s forming thefirst and second electrodes 234, 236 are substantially in therelationships described below under conditions that satisfyT11+T12+T13=T1>T2=T21+T22+T23.

Ir layers 234A, 236C T11:T21=1:0.7

IrOx layers 234B, 236B T12:T22=0.3:1

Pt layers 234C, 236A T13:T23=3:1

The reasons for adopting such layer thickness relationships are asfollows. First, regarding the Ir layers 234A, 236C, since the Ir layer234A in the first electrode 234 functions as an orientation controllayer, a predetermined layer thickness is necessary in order to impartorientation properties, whereas the purpose of the Ir layer 236C of thesecond electrode 236 is to lower resistance, and lower resistance can beobtained the thinner the layer is.

Next, regarding the IrOx layers 234B, 236B, barrier properties againstreductive obstructive factors from below and above the capacitor 230 areobtained by joint use of other barrier layers (the second layer member214, the reducing gas barrier layer 240, and the etching stoplayers/reducing gas barrier layers 140, 280), and the IrOx layer 234B ofthe first electrode 234 is formed having a small thickness, but thethickness of the IrOx layer 236B of the second electrode is increased tocompensate for low barrier properties in the second plug 228.

Lastly, regarding the Pt layers 234C, 236A, the Pt layer 234C in thefirst electrode 234 functions as a seed layer for determining thepreferred orientation of the pyroelectric body 232, and therefore musthave a predetermined layer thickness, whereas the purpose of the Ptlayer 236A of the second electrode 236 is to function as an orientationalignment layer aligned with the orientation of the pyroelectric body232, and the Pt layer 236A may therefore be formed with a smallerthickness than the Pt layer 234C in the first electrode 234.

The thickness ratio of the Ir layer 234A, IrOx layer 234B, and Pt layer234C of the first electrode 234 is set so that T11:T12:T13=10:3:15, forexample, and the thickness ratio of the Ir layer 236C, IrOx layer 236B,and Pt layer 236A of the second electrode 236 is set so thatT21:T22:T23=7:10:5, for example.

The thermal conductivity λ3 of Pt is equal to 71.6 (W/m·K), and thethermal conductivity λ1 of Ir is equal to 147 (W/m·K), which issubstantially twice the thermal conductivity λ3 of Pt. The thermalconductivity λ2 of IrOx varies according to the temperature or theoxygen/metal ratio (O/M), but does not exceed the thermal conductivity21 of Ir. When the layer thickness relationships and thermalconductivity relationships described above are substituted intoEquations (1) and (2) to calculate the size relationship between G1 andG2, it is apparent that G1<G2. Thus, even when the first and secondelectrodes 234, 236 are endowed with a multilayer structure as in thepresent embodiment, the expression G1<G2 is satisfied from therelationship of the thermal conductivities and layer thicknesses.

When the first electrode 234 has the adhesive layer 234D on the bondedsurface with the support member 210 as described above, the thermalconductance G1 of the first electrode 234 is reduced, and therelationship G1<G2 is easily satisfied.

Since the etching mask of the capacitor 230 degrades as etchingproceeds, the side walls of the capacitor 230 acquire a tapered shapewhich is narrower at the top and wider at the bottom as shown in FIG. 1,the more layers are added to the structure. However, since the taperangle with respect to the horizontal surface is about 80 degrees,considering that the total height of the capacitor 230 is on the orderof nanometers, the increase in surface area of the first electrode 234with respect to the second electrode 236 is small. The amount of heattransferred by the first electrode 234 can thereby be kept smaller thanthe amount of heat transferred by the second electrode 236, based on therelationship between the thermal conductance values of the first andsecond electrodes 234, 236.

3.3 Modifications of the Capacitor Structure

A single-layer structure and multilayer structure are described abovefor the first and second electrodes 234, 236 of the capacitor 230, butvarious other combinations of structures are possible which produce thethermal conductance relationship G1<G2 while maintaining the function ofthe capacitor 230.

First, the Ir layer 236C of the second electrode 236 may be omitted. Thereason for this is that in this case, the object of lowering resistanceis achieved in the same manner when Ir, for example, is used as thematerial of the second plug 228. Through this configuration, since thethermal conductance G2 of the second electrode 236 is greater than inthe case shown in FIG. 1, the relationship G1<G2 is easily satisfied. Areflective surface for defining L=λ/4 shown in FIG. 1 takes the place ofthe Pt layer 236A of the second electrode 236 in this case, but amultiple reflection surface can be maintained in the same manner.

Next, the thickness of the IrOx layer 236B in the second electrode 236in FIG. 1 may be made equal to or less than the thickness of the IrOxlayer 234B in the first electrode 234. As described above, since thebarrier properties against reductive obstructive factors from below andabove the capacitor 230 are obtained by joint use of other barrierlayers (the second layer member 214, the reducing gas barrier layer 240,and the etching stop layers/reducing gas barrier layers 140, 280), whenthe reducing gas barrier properties in the second plug 228 are increasedby the configuration shown in FIG. 5, for example, there is no need forthe thickness of the IrOx layer 236B in the second electrode 236 to begreater than the thickness of the IrOx layer 234B in the first electrode234. Through this configuration, the thermal conductance G2 of thesecond electrode 236 further increases, and the relationship G1<G2 iseasier to obtain.

Next, the IrOx layer 234B in the first electrode 234 may be omitted.Crystal continuity between the Ir layer 234A and the Pt layer 234C isnot hindered by omission of the IrOx layer 234B, and no problems occurwith regard to crystal orientation. When the IrOx layer 234B is omitted,the capacitor 230 has no barrier layer with respect to reductiveobstructive factors from below the capacitor 230. However, the secondlayer member 214 is present in the support member 210 for supporting thecapacitor 230, and the etching stop layer 140 is present on the lowersurface of the support member 210, and when the second layer member 214and the etching stop layer 140 are formed by layers having reducing gasbarrier properties, barrier properties with respect to reductiveobstructive factors from below the capacitor 230 can be maintained inthe capacitor 230.

When the IrOx layer 234B in the first electrode 234 is omitted in thisarrangement, the thermal conductance G1 of the first electrode 234increases. It may therefore be necessary to increase the thermalconductance G2 of the second electrode 236 as well in order to obtainthe relationship G1<G2. In this case, the IrOx layer 236B in the secondelectrode 236 may be omitted, for example. Once the IrOx layer 236B isomitted, the Ir layer 236C is also no longer necessary. The reason forthis is that the Pt layer 236A functions as a low-resistance layerinstead of the Ir layer 236C. Barrier properties with respect toreductive obstructive factors from above the capacitor 230 can bemaintained by the reducing gas barrier layer 240 described above, thebarrier metal 228A shown in FIG. 4, or the reducing gas barrier layer290 shown in FIG. 5.

When the second electrode 236 shown in FIG. 1 is formed only by the Ptlayer 236A as described above, the first electrode 234 may be formed bythe Pt layer 234C as a single layer, by the Ir layer 234A and Pt layer234C as two layers, or by the Ir layer 234A of FIG. 1, the IrOx layer234B, and the Pt layer 234C as three layers. In any of these cases, therelationship G1<G2 can easily be obtained by making the thickness T11 ofthe Ir layer 234A of the first electrode 234 greater than the thicknessT21 of the Pt layer 236A of the second electrode 236 (T11>T21), forexample.

4. Electronic Instrument

FIG. 6 shows an example of the configuration of an electronic instrumentwhich includes the pyroelectric detector or pyroelectric detectiondevice of the present embodiment. The electronic instrument includes anoptical system 400, a sensor device (pyroelectric detection device) 410,an image processor 420, a processor 430, a storage unit 440, anoperating unit 450, and a display unit 460. The electronic instrument ofthe present embodiment is not limited to the configuration shown in FIG.6, and various modifications thereof are possible, such as omitting someconstituent elements (e.g., the optical system, operating unit, displayunit, or other components) or adding other constituent elements.

The optical system 400 includes one or more lenses, for example, a driveunit for driving the lenses, and other components. Such operations asforming an image of an object on the sensor device 410 are alsoperformed. Focusing and other adjustments are also performed as needed.

The sensor device 410 is formed by arranging the pyroelectric detector200 of the present embodiment described above in two dimensions, and aplurality of row lines (word lines, scan lines) and a plurality ofcolumn lines (data lines) are provided. In addition to the opticaldetector arranged in two dimensions, the sensor device 410 may alsoinclude a row selection circuit (row driver), a read circuit for readingdata from the optical detector via the column lines, an A/D conversionunit, and other components. Image processing of an object image can beperformed by sequentially reading data from optical detectors arrangedin two dimensions.

The image processor 420 performs image correction processing and variousother types of image processing on the basis of digital image data(pixel data) from the sensor device 410.

The processor 430 controls the electronic instrument as a whole andcontrols each block within the electronic instrument. The processor 430is realized by a CPU or the like, for example. The storage unit 440stores various types of information and functions as a work area for theprocessor 430 or the image processor 420, for example. The operatingunit 450 serves as an interface for operation of the electronicinstrument by a user, and is realized by various buttons, a GUI(graphical user interface) screen, or the like, for example. The displayunit 460 displays the image acquired by the sensor device 410, the GUIscreen, and other images, for example, and is realized by a liquidcrystal display, an organic EL display, or another type of display.

A pyroelectric detector of one cell may thus be used as an infraredsensor or other sensor, or the pyroelectric detector of one cell may bearranged along orthogonal axes in two dimensions to form the sensordevice 410, in which case a heat (light) distribution image can beprovided. This sensor device 410 can be used to form an electronicinstrument for thermography, automobile navigation, a surveillancecamera, or another application.

As shall be apparent, by using one cell or a plurality of cells ofpyroelectric detectors as a sensor, it is possible to form an objectanalysis instrument (measurement instrument) for analyzing (measuring)physical information of an object, a security instrument for detectingfire or heat, an FA (factory automation) instrument provided in afactory or the like, and various other electronic instruments.

FIG. 7A shows an example of the configuration of the sensor device 410shown in FIG. 6. This sensor device includes a sensor array 500, a rowselection circuit (row driver) 510, and a read circuit 520. An A/Dconversion unit 530 and a control circuit 550 may also be included. Aninfrared camera or the like used in a night vision instrument or thelike, for example, can be realized through the use of the sensor devicedescribed above.

A plurality of sensor cells is arrayed (arranged) along two axes asshown in FIG. 2, for example, in the sensor array 500. A plurality ofrow lines (word lines, scan lines) and a plurality of column lines (datalines) are also provided. The number of either the row lines or thecolumn lines may be one. In a case in which there is one row line, forexample, a plurality of sensor cells is arrayed in the direction(transverse direction) of the row line in FIG. 7A. In a case in whichthere is one column line, a plurality of sensor cells is arrayed in thedirection (longitudinal direction) of the column line.

As shown in FIG. 7B, the sensor cells of the sensor array 500 arearranged (formed) in locations corresponding to the intersectionpositions of the row lines and the column lines. For example, a sensorcell in FIG. 7B is disposed at a location corresponding to theintersection position of word line WL1 and column line DL1. Other sensorcells are arranged in the same manner.

The row selection circuit 510 is connected to one or more row lines, andselects each row line. Using a QVGA (320×240 pixels) sensor array 500(focal plane array) such as the one shown in FIG. 7B as an example, anoperation is performed for sequentially selecting (scanning) the wordlines WL0, WL1, WL2, . . . WL239. In other words, signals (wordselection signals) for selecting these word lines are outputted to thesensor array 500.

The read circuit 520 is connected to one or more column lines, and readseach column line. Using the QVGA sensor array 500 as an example, anoperation is performed for reading detection signals (detectioncurrents, detection charges) from the column lines DL0, DL1, DL2, . . .DL319.

The A/D conversion unit 530 performs processing for A/D conversion ofdetection voltages (measurement voltages, attained voltages) acquired inthe read circuit 520 into digital data. The A/D conversion unit 530 thenoutputs the A/D converted digital data DOUT. Specifically, the A/Dconversion unit 530 is provided with A/D converters corresponding toeach of the plurality of column lines. Each A/D converter performs A/Dconversion processing of the detection voltage acquired by the readcircuit 520 in the corresponding column line. A configuration may beadopted in which a single A/D converter is provided so as to correspondto a plurality of column lines, and the single A/D converter is used intime division for A/D conversion of the detection voltages of aplurality of column lines.

The control circuit 550 (timing generation circuit) generates variouscontrol signals and outputs the control signals to the row selectioncircuit 510, the read circuit 520, and the A/D conversion unit 530. Acontrol signal for charging or discharging (reset), for example, isgenerated and outputted. Alternatively, a signal for controlling thetiming of each circuit is generated and outputted.

Several embodiments are described above, but it will be readily apparentto those skilled in the art that numerous modifications can be madeherein without substantively departing from the new matter and effectsof the present invention. All such modifications are thus included inthe scope of the present invention. For example, in the specification ordrawings, terms which appear at least once together with different termsthat are broader or equivalent in meaning may be replaced with thedifferent terms in any part of the specification or drawings.

GENERAL INTERPRETATION OF TERMS

In understanding the scope of the present invention, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. Also, the terms “part,” “section,” “portion,” “member” or“element” when used in the singular can have the dual meaning of asingle part or a plurality of parts. Finally, terms of degree such as“substantially”, “about” and “approximately” as used herein mean areasonable amount of deviation of the modified term such that the endresult is not significantly changed. For example, these terms can beconstrued as including a deviation of at least ±5% of the modified termif this deviation would not negate the meaning of the word it modifies.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. Furthermore, the foregoing descriptions of theembodiments according to the present invention are provided forillustration only, and not for the purpose of limiting the invention asdefined by the appended claims and their equivalents.

1. A pyroelectric detector comprising: a support member including afirst side and a second side opposite from the first side, with thefirst side facing a cavity; a capacitor including a pyroelectric bodybetween a first electrode and a second electrode such that an amount ofpolarization varies based on a temperature, the capacitor being mountedand supported on the second side of the support member with the firstelectrode being disposed on the second side of the support member, athermal conductance of the first electrode being less than a thermalconductance of the second electrode; and a fixing part supporting thesupport member.
 2. The pyroelectric detector according to claim 1,wherein the first electrode has a greater thickness than the secondelectrode.
 3. The pyroelectric detector according to claim 2, whereinthe first electrode, the second electrode, and the pyroelectric body arepreferentially-oriented in a prescribed crystal plane, the firstelectrode has a seed layer for preferentially-orienting the pyroelectricbody in the prescribed crystal plane, the second electrode has anorientation alignment layer in a position contacting the pyroelectricbody with crystal orientation of the orientation alignment layer beingaligned with crystal orientation of the pyroelectric body, and the seedlayer has a greater thickness than the orientation alignment layer. 4.The pyroelectric detector according to claim 3, wherein the firstelectrode further includes an orientation control layer forpreferentially-orienting the seed layer in the prescribed crystal plane,the orientation control layer being disposed between the support memberand the seed layer.
 5. The pyroelectric detector according to claim 4,wherein the first electrode further includes a first reducing gasbarrier layer having barrier properties with respect to a reducing gas,the first reducing gas barrier layer being disposed between the seedlayer and the orientation control layer.
 6. The pyroelectric detectoraccording to claim 5, wherein the first electrode further includes anadhesive layer between the orientation control layer and the supportmember.
 7. The pyroelectric detector according to claim 5, wherein thesecond electrode further includes a second reducing gas barrier layerhaving barrier properties with respect to a reducing gas, with theorientation alignment layer being disposed between the second reducinggas barrier layer and the pyroelectric body.
 8. The pyroelectricdetector according to claim 7, wherein the second electrode furtherincludes a low-resistance layer, with the second reducing gas barrierlayer being disposed between the low-resistance layer and theorientation control layer, and the orientation control layer and thelow-resistance layer are made of the same material, and the orientationcontrol layer has a greater thickness than the low-resistance layer. 9.The pyroelectric detector according to claim 7, wherein the firstreducing gas barrier layer and the second reducing gas barrier layer aremade of the same material, and the first reducing gas barrier layer hasa greater thickness than the second reducing gas barrier layer.
 10. Thepyroelectric detector according to claim 7, wherein the first reducinggas barrier layer and the second reducing gas barrier layer are made ofthe same material, and the second reducing gas barrier layer has agreater thickness than the first reducing gas barrier layer.
 11. Thepyroelectric detector according to claim 3, wherein the prescribedcrystal plane is a (111) plane.
 12. The pyroelectric detector accordingto claim 1, further comprising a light-absorbing member configured totransmit heat obtained by absorption of light to the capacitor, thelight-absorbing member being disposed on an upstream side of thecapacitor with respect to an incidence path of light incident to thesecond electrode of the capacitor, and the second electrode beingconfigured to reflect the light passed through the light-absorbingmember to the light-absorbing member.
 13. A pyroelectric detectiondevice comprising: a plurality of the pyroelectric detectors accordingto claim 1 arranged in two dimensions along two axes.
 14. A pyroelectricdetection device comprising: a plurality of the pyroelectric detectorsaccording to claim 2 arranged in two dimensions along two axes.
 15. Apyroelectric detection device comprising: a plurality of thepyroelectric detectors according to claim 3 arranged in two dimensionsalong two axes.
 16. A pyroelectric detection device comprising: aplurality of the pyroelectric detectors according to claim 4 arranged intwo dimensions along two axes.
 17. A pyroelectric detection devicecomprising: a plurality of the pyroelectric detectors according to claim5 arranged in two dimensions along two axes.
 18. A pyroelectricdetection device comprising: a plurality of the pyroelectric detectorsaccording to claim 6 arranged in two dimensions along two axes.
 19. Anelectronic instrument comprising: the pyroelectric detector according toclaim
 1. 20. An electronic instrument comprising: the pyroelectricdetection device according to claim 13.